A magnetic compass is a device for determining direction. Typically, it includes a magnetized needle supported for rotation within a capsule or casing having a transparent cover. The needle, which acts as a pointer, aligns itself with the earth's magnetic field, a scale to specify direction relative to this magnetic field. The scale may be marked in degrees, for instance. The compasses may make use of iron alloys or ferrite magnets capable of permanently maintaining a strong magnetization. In a magnetic compass, it is conventional to mount the needle on a pointed staff serving as a fulcrum, the point of the staff being received in a jewel bearing to minimize the friction so that the needle is free to tilt as well as to rotate.
Document U.S. Pat. No. 6,105,265 describes a tilt-compensating indicator device for a compass comprising a magnetic field detection device which is mounted on a conical bearing and is accommodated in a housing of the compass. The indicator device is rotatably mounted on the magnetic field detection device by means of a receiving bearing whose bearing shaft, accommodated in bearing elements of the magnetic field detection device, extends substantially at right-angles to the north-south direction of the magnetic field detection device.
Further, document U.S. Pat. No. 6,094,830 discloses a compass comprising an at-least-partially-transparent housing having a top and a bottom, a vertically orientated, conical pivot bearing, and a magnetic detection means which is mounted on the vertically-oriented conical pivot bearing. The magnetic detection means thereby is capable of rotating in a substantially-horizontal plane. The magnetic field detection means is provided with a radially-extending, tilt-compensating, indicator device. The indicator device has at least one spacer element which is spaced from the magnetic field detection means, the spacer element projecting from the indicator device and being directed towards one of a top of the housing of the compass and a bottom of the housing of the compass. By this structure, the indicator device is guidable in the housing of the compass substantially-parallel to at least one of the top of the housing of the compass and the bottom of the housing of the compass by being mechanically pushed off at least from one of the top of the housing of the compass and the bottom of the housing of the compass by the spacer element when the housing is tilted. In addition, the spacer element which is arranged on the indicator device is oriented in respect to the top of the housing of the compass or the bottom of the housing of the compass in such a manner that an abutting of the indicator device against the housing of the compass can be prevented.
Additionally, document U.S. Pat. No. 5,233,759 teaches a tilt-compensating magnetic compass formed by a capsule enclosing a rotatable pointer to indicate direction and a rotatable magnetic-field detector provided with a permanent magnet. The detector, which is rotatable about an axis colinear with the axis about which the pointer rotates, orients itself with respect to the earth's magnetic field, the detector being tiltable to a degree depending on the inclination of the magnetic field and on the attitude of the compass with respect to the horizontal plane. The detector is mechanically linked to the pointer so that rotation of the detector results in a corresponding rotation of the pointer regardless of the degree of tilt, whereby the pointer accurately indicates direction. The linkage consists of a pin projecting from the detector and passing through a slot in a fork extending from the pointer, whereby when the detector tilts, the pin then shifts within the slot, but remains coupled to the fork to maintain the linkage without imparting movement to the pointer.
In view of the foregoing, it would be beneficial to provide a device for a compass comprising a tilt-compensating and/or inclination-compensating indicator device. Such device for a compass should be capable of being manufactured simply, cost effectively, and in industrial scale.